# deficiency

/dɪˈfɪʃənsi/ (US) · /dɪfˈɪʃənsi/ (UK)

Source: https://englishreference.com/word/deficiency
Updated: 2026-06-20

## Senses

### 1. lack of a nutrient

noun · CEFR C1 · Technical

a lack of something your body needs to stay healthy, like a vitamin.

For teachers: an insufficiency of a substance, such as a vitamin or mineral, that is essential for healthy physiological functioning.

- A vitamin C deficiency can make you feel very tired and weak.
- The patient presented with symptoms consistent with a severe iron deficiency, likely exacerbated by a restrictive diet and high physical activity.

Usage: Often followed by the preposition 'of'.

### 2. a flaw or weakness

noun · CEFR C1 · Formal

a weakness or a way in which something is not good enough.

For teachers: a failure to reach a required standard or a specific flaw in a system, plan, or character.

- The report pointed out a serious deficiency in the school's safety rules.
- The audit identified several structural deficiencies in the company's internal accounting procedures that required immediate rectification.

Usage: Commonly used in formal reports and academic evaluations.

### 3. mathematical gap

noun · CEFR C2 · Technical

a specific measurement of how much a mathematical shape or system is missing.

For teachers: a technical measure of the amount by which a geometric or linear system falls short of a maximum or complete state.

- The professor explained how to calculate the deficiency of the curve.
- In algebraic geometry, the deficiency of a curve relates to the number of double points compared to the maximum possible for its degree.

## Examples

- A vitamin deficiency can make you feel very tired.
- The doctor ordered blood tests to check if a mineral deficiency was causing her frequent headaches.
- The audit highlighted a significant deficiency in the company's internal security protocols, suggesting that current measures were insufficient to prevent data breaches.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.